As we remarked earlier, Carrollian structures appear on generic null surfaces. Hence if we are looking at building field theories which live on generic black hole horizons, it is natural to consider Carrollian theories. (See [1]} for a detailed analysis of the emergence of Carrollian structures on black hole event horizons.) Also, as per our previous argument, if we want degrees of freedom of the theories not to leave the null surface, we must necessarily consider massless or conformal Carrollian theories. There have been attempts at understanding these horizon BMS symmetries in recent times e.g. in [2]}. BMS-invariant field theories thus can act as putative duals for generic black holes. A derivation of the entropy of black holes based on the BMS-Cardy formula [3]} can be found in [4]}, [5]}.
